This invention relates to the production of paperboard, and more particularly to method and apparatus for making multiple ply corrugated or solid fibre paperboard.
Multiple wall corrugated paperboard has been produced heretofore by utilizing as many single facer sections, bridges and double facer glue stations in the corrugator as are required for the number of walls to be produced. Thus, double wall paperboard production has required an arrangement of two single facer sections, two bridges and two glue stations at the double facer. Similarly, triple wall paperboard has required the utilization of three single facer sections, three bridges and three glue stations at the double facer.
The foregoing procedures for producing double and triple wall corrugated paperboards requires an extremely large investment in equipment and in plant floor space to accomodate the equipment. Corrugators have not been provided heretofore with more than three single facer sections, three bridges and three glue stations at the double facer.
Exemplary of the foregoing prior art are the methods and apparatus described in U.S. Pat. Nos. 2,949,151; 3,179,023; 3,290,205; 3,492,188; and 3,977,929.
Four wall corrugated paperboard has been produced by laminating two double wall paperboards. In like manner, five wall corrugated paperboard has been produced by laminating a double wall paperboard and a triple wall papeboard; six wall paperboard has been produced by laminating two triple wall or three double wall paperboards; and so forth. This procedure requires large laminating machinery and substantial floor space. Moreover, it is a very capital and labor intensive process.
The lamination process, with its attendant costly requirements, also is employed in the production of multiple ply solid fibre paperboard from the single shet output of a paster.